This invention relates to a flame retardant polyamide composition containing acrylate based polymers as flame retardants.
A wide variety of flame retardant additives for polyamides are available. However, many of the flame retardant materials are deleterious to the physical properties of polyamides. Typical of such materials are nonpolymeric materials which are nonsoluble in the polyamide matrix. These materials have been found to adversely affect the impact properties of polyamides.
Polymeric flame retardant type materials sold for use in thermoplastic materials have been found to be useful in a variety of polymers. However, these materials, although providing flame retardant properties, have often been found to be not compatible with polyamides. Typical of such materials is polymeric brominated polystyrene. This material has been found to be an effective flame retardant for polyamides. The use of polymeric brominated polystyrene to date has only been in glass filled polyamide compositions. The reason is that polymeric brominated polystyrene is not compatible with polyamides. It is necessary to use a dispersion aid such as short glass filler with the polymeric brominated polystyrene to uniformly distribute it throughout the polyamide matrix. Once this is done, it has been found to be an effective flame retardant.
Acrylate based flame retardant polymers are disclosed in U.S. Pat. Nos. 4,128,709 and 4,301,058, both hereby incorporated by reference. These disclosures disclose a variety of acrylate based polymers for use as flame retardant agents in thermoplastic compositions. Particularly disclosed is the use of pentabromobenzyl polyacrylate in a variety of polymers. However, neither patent discloses the use of such acrylate based polymers as flame retardants in polyamide compositions.